Dandruff is a chronic condition characterized by itchy and flaky skin of the scalp. According to the American Osteopathic College of Dermatology, dandruff occurs because of excessive buildup of dead skin on the scalp, and fall and winter weather can make it worse. Although the itching the results may be uncomfortable and the flaking embarrassing, dandruff is not a serious condition, and topical solutions can control it.
The culprit behind dandruff often is dry skin, which causes the itching and flaking, according to the Mayo Clinic. During colder seasons or in a dry atmosphere that central air conditioning produces, skin loses its moisture and dandruff results
Although excessive washing can strip the skin of natural oils and cause dryness, dandruff also occurs when you don’t wash your hair often enough. Oils, dead skin cells from the scalp and hair products can build up and form the flaky material.
For more severe cases of dandruff, a yeast-like fungus, malassezia, can be the cause. For most people, the normally occurring fungus does not present problems. However, when malassezia feeds on natural oils of the scalp and starts growing out of control, the skin becomes irritated and skin cells start growing faster than usual, according to the Mayo Clinic. Skin cells die and shed all the time, but when excessive dead skin is present, they clump together with scalp oils and appear as flaky dandruff.
Skin disorders such as psoriasis, eczema and seborrheic dermatitis can affect the scalp and contribute to dandruff formation. Psoriasis is characterized by the accumulation of dead skin cells and thick silvery scales, according to the Mayo Clinic. Eczema also produces itchy, dry scales that flake. According to the American Osteopathic College of Dermatology, severe dandruff is closely related to seborrheic dermatitis, an inflammatory skin disorder that results in reddened, greasy skin covered by white or yellow scales. Medline Plus states that the skin disorder occurs from a combination of overproduction of oil and irritation from malassezia.